1. Field of the Invention.
This invention relates generally to rear view mirrors and, more particularly but without limitation, to convex rear view mirrors for vehicles.
2. Description of the Related Art.
To provide a more panoramic view of a rearward view from a vehicle, a rear view mirror mounted exteriorly on the passenger side of the vehicle sometimes has a convex mirror in order to provide a wider range of view for the operator of the vehicle. The convex shape of the mirror causes a trailing car to appear smaller than would be the case if that mirror had a flat or planar reflective surface. This size distortion phenomenon causes the trailing car to appear to be farther away than it actually is, thereby providing the operator of the vehicle with a false sense of security and thereby increasing the possibility of an unsafe lane change, etc.
The method currently used to help prevent such an occurrence is to etch or otherwise provide a note on the mirror stating that the car behind may be closer than it appears. For example, such a note may contain a message such as "OBJECTS IN MIRROR ARE CLOSER THAN THEY APPEAR" or other suitable message. Unfortunately, such a notice does not provide the operator with any indication as to the distance spacing between his vehicle and a trailing vehicle or any indication as to how rapidly the trailing vehicle may be approaching his vehicle.
Many vehicles equipped with a convex rear view mirror are also equipped with a planar rear view mirror, which might provide information upon which a trailing distance or approaching speed could be more accurately estimated, at least for operators having good reliable vision in both eyes. Such planar rear view mirrors are generally mounted either interiorly for viewing through a rear window and/or exteriorly on the operator's side of the vehicle. Many times, the interior rear view mirror is not usable because of articles in a rear seat obstructing the rearward view of that mirror, because there is no rear window, etc. Also, it is not uncommon for the rear view mirror exteriorly mounted on the operator's side of the vehicle to become disabled, such as when two vehicles pass too closely and the mirrors collide, or for various other reasons. In that event, the operator would then generally rely on the convex rear view mirror mounted on the passenger side of the vehicle.
Further, operator's having good reliable eyesight in only one eye may have difficulty judging the spacing between his vehicle and a trailing vehicle or the rate at which a trailing vehicle is overtaking his vehicle even with a planar mirror. The same difficulty may sometimes apply to persons having eyesight in both eyes but whose field of view is limited due to glaucoma or other possible diseases or hindrances.
What is needed is a mechanism that provides the operator of a vehicle with a reliable indication of the spacing between his vehicle and a trailing vehicle and an indication of the speed at which his vehicle is being overtaken by the trailing vehicle.